The crew's main task during their 13-day mission is to carry out China's first manual space docking, a procedure that will take the country a step closer to setting up its own space station by 2020.

But ahead of that, the Shenzhou-9 ("Divine Vessel") and the Tiangong-1 ("Heavenly Palace") module already in orbit will dock automatically at around 0600 GMT, the official Xinhua news agency said, giving a later time than earlier reports.

The astronauts will enter the orbiting Tiangong-1 around 20 minutes later, Xinhua said. Earlier reports said the Shenzhou-9 would remain attached to the space capsule for six days before parting in preparation for manual docking.

China aims to complete construction of a space station by 2020, a goal that requires it to perfect docking technology -- a delicate manoeuvre that the Russians and Americans successfully completed in the 1960s.

The technique is hard to master because the two vessels, placed in the same orbit and revolving around the Earth at thousands of kilometres per hour, must come together very gently to avoid destroying each other.

President Hu Jintao has said the operation would mark a "major breakthrough in the country's manned space programme", which is gearing up just as the United States scales back its space exploration activities.

Docking manually requires huge accuracy and is necessary in case of any problems with the automatic docking, such as in the event the control centre cannot do it remotely from Earth.

The team -- headed by Jing Haipeng, a veteran astronaut on his third space mission -- has rehearsed the procedure more than 1,500 times in simulations.

Liu Wang, who has been in the space programme for 14 years, will be in charge of manual docking manoeuvres, while Liu Yang, China's first woman to travel to space, will conduct aerospace medical experiments and other space tests during the mission.

China sees its space programme as a symbol of its global stature, growing technical expertise, and the Communist Party's success in turning around the fortunes of the once poverty-stricken nation.

Monday will be only the third time that China has performed the highly technical procedure, which brings two vessels together in high-speed orbit. It achieved two similar dockings in November last year.